The Bungee Dunker

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

The Bungee Dunker

Bungee jumping is that crazy sport where you hook a long, stretchy bungee cord onto a bridge or cliff, then jump off while hanging onto it. If you do the math right, you zoom downward until the cord stretches as much as it can…you slow to a stop, then snap back up towards the sky again. If you do the math wrong, you go SPLAT on the ground. To keep this from happening, you leave yourself extra room at the bottom. Well, not this guy. Simon Berry left a cup of tea on a diving board, then bungee-jumped from more than 240 feet above and perfectly dunked a chocolate cookie in it. He had to get far enough down to reach it, but without crashing headfirst into it. But as we see in the video at the bottom, the cookie did make a big splash!

Wee ones: Hold 2 things that won’t break, like a stuffed animal and a bouncy ball. Hold one thing in each hand and drop them from the same height at the same time. Do they reach the ground at the same time? See what happens!

Little kids: If Simon counted down the last 5 seconds before jumping, what numbers did he say? Bonus: If he took 5 seconds to fall and dunk the cookie, then 5 seconds to snap back up, how many seconds did his whole bungee trip take?

Big kids: Simon fell 240 feet 10 inches, then zoomed back up 240 feet 10 inches. How far did he zoom through the air in total, in feet and inches? Bonus: If halfway down Simon started screaming in panic, how much farther did he have left to fall to reach the cup of tea?

The sky’s the limit — literally: If your bungee cord lets you fall 1 foot the 1st second, then 3 more feet during the 2nd second, then 5 more feet during the 3rd second…will you fall 49 feet in a round number of seconds? And can you tell quickly without adding up all the numbers?

Answers:

Wee ones: Unless one of the things you drop catches air and floats (like a piece of paper), they should hit the ground at the same time!

The sky’s the limit — literally: Yes! You might have noticed that each time you add the next odd number, you get a new “perfect square” as the total — a number that is some other number times itself (1×1, 2×2, 3×3, and so on). You get 1 foot in total, then 4 feet total after 2 seconds, 9 feet after 3 seconds…so you’ll reach 49 feet in 7 seconds.

About the Author

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.